The extreme space weather event in 1903 October/November: An outburst from the quiet Sun

Occurring in the weak Solar Cycle 14 just after its minimum, the extreme space weather event in 1903 October-November is one of these cases. Here, we reconstruct the time series of geomagnetic activity based on contemporary observational records.

With the mid-latitude magnetograms, the 1903 magnetic storm is thought to be caused by a fast coronal mass ejection (1500 km s(-1)) and is regarded as a superstorm with an estimated minimum of the equivalent disturbance storm time index (Dst') of -531 nT. The reconstructed time series has been compared with the equatorward extension of auroral oval (441 in invariant latitude) and the time series of telegraphic disturbances.